How to measure how much solar we need?
(hope this is right section) Brought home TT last month and now have basics taken care of and RV is road ready. Now starting to think about bigger long term projects. One project is, we would like...
Forum Discussion
You can get your theoretical AH daily haul for any solar wattage amount for a location and time of year, but that is normally way more of an AH haul than you will use, mostly due to the way battery charging works.
The batteries get high in SOC later in the day and then the only way to get at the solar "going to waste" is to run other loads besides battery charging.
When I did my AH haul testing, I ran loads the whole daylight time so the batteries could not reduce the recorded haul. With MPPT, that also keeps battery voltage low all day further enhancing the amps and so the AH haul. In real life you would not do that since you do want to charge those batteries up before dark and solar shuts off.
In theory or during such a test, the afternoon AH haul is a mirror image of the morning haul. So you can actually just run the test from solar wake-up till high noon and double the haul. But then you have different horizons at dawn and dusk such as mountains or trees that can spoil the perfect mirror image too.
With 130w at 49.3N in May testing, I got 56AH flat, 70AH tilted, and 90AH tracking. It is all proportionate so with 230w now, I would get
99AH flat, 124AH tilted, and 159AH tracking.
All those numbers are good for is comparing set-ups. Then you could say, whatever the actual cloud amount vs sunshine in any day, which set-up would get you more AH, but not be able to say how many.
The batteries get high in SOC later in the day and then the only way to get at the solar "going to waste" is to run other loads besides battery charging.
When I did my AH haul testing, I ran loads the whole daylight time so the batteries could not reduce the recorded haul. With MPPT, that also keeps battery voltage low all day further enhancing the amps and so the AH haul. In real life you would not do that since you do want to charge those batteries up before dark and solar shuts off.
In theory or during such a test, the afternoon AH haul is a mirror image of the morning haul. So you can actually just run the test from solar wake-up till high noon and double the haul. But then you have different horizons at dawn and dusk such as mountains or trees that can spoil the perfect mirror image too.
With 130w at 49.3N in May testing, I got 56AH flat, 70AH tilted, and 90AH tracking. It is all proportionate so with 230w now, I would get
99AH flat, 124AH tilted, and 159AH tracking.
All those numbers are good for is comparing set-ups. Then you could say, whatever the actual cloud amount vs sunshine in any day, which set-up would get you more AH, but not be able to say how many.
